This section provides background information related to the present disclosure which is not necessarily prior art.
A model of a typical ultrasonic tube sealer 100 is shown in FIG. 1. Typical components of ultrasonic tube sealer 100 include an ultrasonic transducer 102, a booster 104, and an ultrasonic horn 106. Electrical energy from a power supply 101 at a frequency of 20-60 kHz is converted to mechanical energy by the ultrasonic transducer 102. The mechanical energy converted in the ultrasonic transducer 102 is transmitted to a tube 108 to be sealed through the booster 104 and the ultrasonic horn 106. The booster 104 and the ultrasonic horn 106 perform the functions of transmitting the mechanical energy as well as transforming mechanical vibrations from the ultrasonic transducer 102 by a gain factor.
The mechanical vibration that results on an ultrasonic horn tip 110 is the motion that performs the task of sealing the tube 108. Ultrasonic horn tip 110 illustratively includes one or more forming tools (not shown) on sides of ultrasonic horn tip 110. A portion of the tube 108 to be sealed, typically an end portion 112, is placed between ultrasonic horn tip 110 and an anvil tip 114 of an anvil 116 and supported by anvil tip 114. Anvil tip 114 illustratively includes a forming tool (not shown). The forming tool of ultrasonic horn tip 110 is brought into contact with end portion 112 of tube 108 pinching end portion 112 between the forming tool of ultrasonic horn tip 110 and the forming tool of anvil tip 114. Typically, ultrasonic horn tip 110 is brought to a pre-determined distance from anvil tip 114 so that there is a pre-set gap between the forming tools of ultrasonic horn tip 110 and anvil tip 114 in which the end portion 112 of tube 108 to be sealed is situated. Ultrasonic vibrations are applied via the ultrasonic horn tip 110 to end portion 112 of tube 108. The ultrasonic vibrations generate heat to bond the material of the end portion 112 of tube 108 together where end portion 112 is pinched between the forming tools of ultrasonic horn tip 110 and anvil tip 114. The forming tools of ultrasonic horn tip 110 and anvil tip 114 also form the end portion 112 of tube 108, such as by cutting it. The electrical energy provided by power supply 101 is then stopped and the end portion 112 of tube 108 held closed between the forming tools of ultrasonic horn tip 110 and anvil tip 114 for a brief period of time. An examples of such a prior art ultrasonic tube sealer is the Branson Ultraseal® Ultrasonic Tube Welding System available from Branson Ultrasonics Corporation, Danbury, Conn.
Typically, the forming tools of ultrasonic horn tip 110 and the anvil tip 114 form the end portion 112 of the tube 108 to be a square end. That is, a distal edge and two opposed side edges of the end portion 112 are sides of a square (or rectangle). For example, the forming tools of ultrasonic horn tip 110 and anvil tip 114 cut the end portion 112 of tube 108 with a square cut when they pinch the end portion 112 of tube 108 between them. This square end can have sharp edges can present the risk of cuts if not handled with care by those handling the sealed tube 108, such as the operator of the ultrasonic tube sealer and packagers of the sealed tube 108.